Geological Control of Petroleum Type

Abstract

Regularities in crude oil and gas composition have been observed for a long time. Some of those seem to have a regional significance, e.g., geologists know that crude oils from the Middle East are generally rich in sulfur, while oils from North Africa have a low sulfur content. Other regularities seem to be more general: for instance, in several places of the world, it has been observed that oil density decreases with depth; more generally, geochemists and refiners have observed that crude oil density, sulfur content, and viscosity are closely related.